The present invention relates to apparatus for transporting rod-shaped articles which constitute or form part of smokers' products, and more particularly to improvements in apparatus for pneumatically transporting filter rod sections or analogous rod-shaped articles between producing and processing machines.
It is already known to transport filter rod sections from a maker (e.g., a filter rod making machine which produces and delivers a file of discrete filter rod sections of multiple unit length) to one or more consuming or processing machines by resorting to pneumatic conveyors. Such transporting apparatus normally comprise a pneumatic sender which receives rod-shaped articles from the maker and introduces successive articles into the inlet of a pneumatic conveyor. The latter advances the file of successive articles to a receiver which, in turn, admits the articles into the magazine of a processing machine, e.g., into the magazine of a filter tipping machine wherein filter rod sections are united with plain cigarettes to form filter cigarettes of unit length or multiple unit length. As a rule, the receiver comprises a speed uniformizing device which delivers successive articles issuing from the pneumatic conveyor to an accelerating device so that successive articles of the file develop gaps which allow for conversion of the file into one or more rows wherein the articles travel sideways (i.e., transversely of their axes) and are fed into the magazine of the processing machine. Apparatus of the just outlined character are especially suited for transport of filter rod sections through considerable distances, e.g., from a battery of makers which are installed in one part of the manufacturing plant to a battery of processing machines which are grouped in another part of the same plant. It is also known to install a reservoir system between the maker and the corresponding sender or senders so as to ensure that eventual fluctuations in the rate at which a maker delivers rod-shaped articles and/or in the rate at which the sender is to deliver articles to a processing machine can be compensated for by increasing or reducing the supply of articles in the reservoir system. Suitable monitoring devices (e.g., photocells) can be installed in the pneumatic conveyor of each transporting apparatus in order to ascertain the presence or absence of rod-shaped articles in the pipeline.
German Offenlegungsschrift No. 1,432,688 discloses a pneumatic transporting apparatus wherein a sender delivers filter rod sections into the inlet of a pneumatic conveyor and the latter delivers the filter rod sections to the processing machine. In order to ensure that an adequate supply of articles is always present upstream of the processing machine, and to further ensure that clogging of the pneumatic conveyor is detected without appreciable delay, the apparatus which is disclosed in this German publication comprises two photocells which are adjacent to the path of travel of filter rod sections in the pneumatic conveyor and are disposed one after the other. Signals which are generated by such photocells are used to regulate the admission of filter rod sections into the pneumatic conveyor.
German Offenlegungsschrift No. 1,532,253 discloses an apparatus which delivers filter rod sections to a filter tipping machine. The apparatus comprises a sender, a receiver which is connected with the magazine of the filter tipping machine, and a pneumatic conveyor connecting the outlet of the sender with the inlet of the receiver. The path which is defined by the pneumatic conveyor is monitored by two photocells which are installed one after the other and serve the dual purpose of regulating the admission of filter rod sections into the pneumatic conveyor as well as of detecting eventual pileups of articles in the pipeline.
A serious drawback of the above described conventional transporting apparatus is that the monitoring devices which are adjacent to the pneumatic conveyor can detect the existence of defects and/or malfunctions only after the fact, i.e., relatively soon or with a certain delay after the occurrence of a malfunction. For example, if the monitoring devices are designed to scan the path which is defined by the pneumatic conveyor for the presence or absence of a pileup, the detection of a pileup will take place with a certain delay after the development of malfunction or malfunctions which have initiated the pileup in the pneumatic conveyor. In other words, conventional monitoring devices are incapable of detecting eventual malfunctions as soon as they occur, and they are evidently incapable of detecting the development of potential causes of malfunctions so as to enable an attendant to eliminate such potential causes of malfunctions before they can adversely influence the output of the processing machine, totally clog the pneumatic conveyor and/or cause the production of a large number of defective rod-shaped articles.